1. Field of the Invention
The present invention relates to a magnetic recording/reproducing device and suitable particularly for an application to a device for recording and reproducing desired information signals by helically scanning a magnetic tape with rotary heads.
2. Description of the Prior Art
A conventional magnetic recording/reproducing device, has a digital video tape recorder for helically scanning a magnetic tape with rotary heads and thereby effecting record/reproduction of information signals consisting of, e.g., digital video signals on and from recording tracks formed obliquely to a traveling direction of the magnetic tape.
This type of digital video tape recorder includes a D-1 format digital video tape recorder, based on so-called SMPTE (American Movie & Television Engineer Association) standards, for recording and reproducing component digital video signals and also a D-2 format digital video tape recorder, based on the SMPTE standards, for recording and reproducing composite digital video signals. Both of the devices record the video signals for one field over the plurality of recording tracks.
A so-called guard band recording is adopted in the D-1 format digital video tape recorder. As illustrated in FIG. 7(A), the digital video signals are recorded on a magnetic tape 1 in format in which guard bands GB are interposed between respective recording tracks T11, T12, T13, T14, T15, T16, . . . , T1N.
So-called azimuth solid recording is adopted in the D-2 format digital video tape recorder. As illustrated in FIG. 7(B), the digital video signals are recorded on recording tracks T21, T22, T23, T24, T25, T26, . . . , T2N having sequentially alternately different azimuths on the magnetic tape 1.
The recording tracks T1N based on the D-1 format shown in FIG. 7(A) are formed in the direction inclined to the traveling direction of the magnetic tape 1 with the guard bands GB being interposed between the respective tracks. Digital audio signals AD for 4 channels are recorded on the central parts thereof, while digital video signals VD1, VD2 are recorded on upper and lower parts thereof. Note that in the case of the D-1 format, the digital video signals VD1, VD2 for one field are recorded on, e.g., 10 or 12 pieces of the recording tracks T1N.
The recording tracks T2N based on the D-2 format shown in FIG. 7(B) are formed in the direction inclined to the traveling direction of the magnetic tape 1 having sequentially different azimuths. The digital video signals VD are recorded on the central parts thereof. Digital video audio signals A1, A2, A3, A4 for 4 channels are recorded on upper and lower parts thereof by a double recording method. Note that in the case of the D-2 format, the digital video signals VD for one field are recorded on, e.g., six pieces of recording tracks T2N.
In the digital video tape recorders described above, if track pitches of the recording tracks are narrowed to improve the recording density, the efficiency is poor corresponding to the existence of the guard bands in the D-1 format guard band record. This results in a problem in that the track pitch is widened.
The D-2 format digital video tape recorder adopts the azimuth solid recording using no guard band and is therefore considered to be fundamentally suitable for ameliorating the recording density by narrowing the track pitches of the recording tracks.
When the track pitches of the recording tracks are further narrowed, however, and if a tracking error is caused on the occasion of effecting an editing process by overwriting, as depicted in FIG. 8, an old recording track T24 having an equiphase azimuth contain some unerased portions at this overwrite starting part T21N. A problem is thereby caused, wherein the S/N ratio is deteriorated, and the error rate during the reproduction deteriorates so as to cause a decline of image quality.
As depicted in FIG. 9, if the tracking error is produced when only one-channel information of the digital audio signals is to be replaced, the same problem occurs. Some unerased portions of the old recording tracks A1 having the equiphase azimuth exist for of digital audio signal A1N which are to be replaced, resulting in noises.
For eliminating the remainder of such old recording tracks T24, A1 having the equiphase azimuth, the old recording tracks T24, A1 can be erased in advance of the overwrite recording by use of a flying erase head.
In this case, however, if a head width of the flying erase head is selectively set to a value which is narrower than a track width of the recording track, a problem occurs because the old recording tracks having equiphase are left on both sides. Whereas if set to a value wider than the track width of the recording track, the two necessary adjacent recording tracks are erased, making it difficult to form the guard band. This is not acceptable in actual equipment.